FYI, I work for OpenNMS, so I can't answer for all systems, but I can tell you how we stack up against your requirements:

OpenNMS was started by guys who did OpenView, NetCool, and other consulting for years and were tired of crappy tools that were hard to integrate with, so it was designed with scalability and "enterprise-ness" from the start. We've got folks monitoring hundreds of thousands of data points every 5 minutes from a single box. At this point the biggest bottleneck is not the code, but the I/O capabilities of your monitoring host, and how much data it can save to disk in a given amount of time.

OpenNMS can do this, with a combination of our syslog daemon (which turns syslog messages into events), the event translator (which can parse those events and let you look for certain patterns to make more specific/different events), and alarms, which collapse multiple events of the same type into a single thing which you would then use to send notifications (which can span various groups, duty schedules, and notification types).

OpenNMS has a number of ways to integrate external systems:

* traps - OpenNMS can receive SNMP traps and turn them into events internally

* event socket - OpenNMS has an event socket that you can push XML to that become events internally

* syslog (as mentioned earlier)

* "passive status" which lets you essentially "push" polled data instead of querying it from a remote device

I'm a coder, I don't do any of our field-implementation consulting, so there are probably more ways to integrate that I've forgotten, but basically at this point, there's nothing you'd want to integrate that couldn't be integrated with just a little glue scripting.

That said...

There is no perfect monitoring system. Everyone (including me... <g>) starts out thinking "eh, network management can't be that complicated" but it turns out everyone has wildly different networks, different needs, and in the end, will get the most out of different solutions. Any network management tool that says it can solve everyone's problems is lying. There are absolutely situations where some tool would work better for your specific needs than OpenNMS, but we've worked hard to provide a platform that eases integration, to cover as many of those needs as possible. So far, all of the stuff you've mentioned is doable in OpenNMS. Not all of it would happen out of the box, but all of the things you're wanting are possible due to our flexible integration points.

Honestly, I'm not very familiar with SMARTS, but we don't do a ton of root cause analysis out of the box.

We do have an integration with Drools to be able to do correlation and root cause analysis, but we don't have much in the way of default configuration for it at the moment.

Yeah, the web UI code is the cruftiest part of OpenNMS, and it's next on our list to tackle/modernize. It's last in the list since the most important part is the backend, and notifications. Day-to-day, the web UI is more important to managers that want to see pretty graphs, and the notification system is for the folks doing real work responding to issues. ;)

We've already started taking steps towards that, implementing a RESTful interface for the backend parts of the system. Now we need to make a nice UI that takes advantage of it...

That would definitely be a bug. I'll look into it... :)

And this is why we (OpenNMS) don't play the per-node. It's not any harder to run OpenNMS when managing 1000 nodes than when managing 100, you only need to scale hardware appropriately. Per-node pricing is an artificial limitation.

We also don't play the "you get a special price behind closed doors" game, our support prices are public, fair, and the same for everyone -- and that's only if you need commerical support -- our prices are $0 if you don't need or want support.

If you do the math, it's $0 for the software, plus $14,995/year for support for any number of nodes, and the software is 100% open-source and fully capable of replacing or exceeding OpenView. ;)